Mysore thorn (Caesalpinia decapetala)

Also known as: wait-a-while

Mysore thorn is a prickly shrub or climber that forms dense thickets. It smothers other vegetation and restricts the movement of people and animals.

Profile

How does this weed affect you?

Mysore thorn plants:

• form dense thickets that restrict access for people and animals, including access to water
• have prickles that can injure people and animals
• invade pastures, reducing productivity
• outcompete and smother native vegetation
• reduce shelter and food for native animals
• restrict water flows and the movement of flood debris, which leads to increased flood damage 
• can damage infrastructure including sheds and fences
• can harbour feral animals.

What does it look like?

Mysore thorn is a prickly, perennial evergreen shrub up to 4 m tall. It can grow up to 20 m high when climbing over supporting vegetation or buildings.

Leaves are:

• 7– 40 cm long
• fern-like and made up of 4 –10 pairs of primary leaf segments, which are further divided into 5 -12 pairs of small leaflets. The leaflets are:
  • dark green on top and paler underneath
  • oblong shaped
  • 7–18 mm long and 2– 6 mm wide
  • hairy on both sides.

Flowers are:

• yellow or pale yellow (occasionally white)
• up to 3 cm wide with 5 petals 
• on stalks up to 2.5 cm long
• in spike-like clusters 5–25 cm long
• at the tip of branches
• present from winter to spring.

Seedpods are:

• greenish-yellow when young, turning brown when mature
• 6–10 cm long and 2–3 cm wide
• oblong and flat with a small, pointed beak at one end
• hairy
• usually present from August to December.

Pods split open when mature, releasing 4–9 seeds.

Seeds are:

• black and brown
• 6–10 mm wide
• round or oval shaped.

Stems are:

• covered in curved or straight prickles 0.5 – 5 mm long
• hairy with fine golden hairs
• rough at the base of the plant with small bumps (lenticels)
• smooth and a creamy-green colour on younger stems.

Similar looking plants

Mysore Thorn is very similar to these other introduced plants: 

• Dwarf poinciana (Caesalpinia gilliesii), which does not have prickles. It also has yellow flowers but with distinctive, long, bright red thread-like stamens.
• Honey locust (Gleditsia triacanthos), which is a tree up to 20 m tall. It has straight spines usually up to 10 cm long and very small, inconspicuous greenish or creamy-yellow flowers.
• Parkinsonia (Parkinsonia aculeata), which also has small, curved prickles. Its flowers have 4 yellow petals and one orange or orange spotted flower.

Where is it found?

In NSW, mysore thorn plants grow in the North Coast, Hunter, Greater Sydney and South East regions.

This plant is native to Japan, China, India and Malaysia. It was originally planted in gardens as a hedge plant.

What type of environment does it grow in?

Mysore thorn grows best in humid coastal conditions in subtropical to tropical climates. It grows on a variety of soil types and tolerates annual rainfall from 300–3000 mm. It often grows:

• in disturbed areas such as roadsides
• in pastures
• along creek banks
• in native grasslands
• along the edges of bushlands and forests.

Maps and records

• Recorded presence of Mysore thorn during property inspections (Map: Biosecurity Information System - Weeds, 2017-2026)
  These records are made by authorised officers during property inspections under the Biosecurity Act 2015. Officers record the presence of priority weeds in their council area and provide this to the NSW Department of Primary Industries. Records reflect the presence of the weed on the date of inspection.
  
  

How does it spread?

By seed

Seeds can stay viable in the soil for up to 10 years. Seeds are spread:

• by animals that feed on the seed pods, including rodents, birds and cattle
• in moving water
• in contaminated soil or mud, which may be on vehicles or machinery. 

References

Acevedo-Rodríguez, P. (2005). Vines and climbing plants of Puerto Rico and the Virgin Islands. Contributions from the United States National Herbarium, 51, 1-483.

Global Invasive Species Database. (2026). Species profile: Caesalpinia decapetala. Retrieved 23 February 2026 from:https://www.iucngisd.org/gisd/speciesname/Caesalpinia+decapetala

Identic Pty Ltd. and Lucid (2016). Environmental Weeds of Australia Fact sheet: Retrieved 23 February 2026 from:https://keyserver.lucidcentral.org/weeds/data/media/Html/caesalpinia_decapetala.htm

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 27 February 2026 from:https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Caesalpinia~decapetala

More information

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Control

Be careful of the prickles when controlling this plant. Ensure that protective clothing is worn to protect your skin and eyes.

Prevention

Clean vehicles or machinery that have been infested areas before leaving the site.

Cattle can spread the seed. To prevent the seeds being spread over a wide area, keep cattle, that have been in infested areas, in a holding paddock before moving them to an area without mysore thorn. Allow time for the seeds to pass through their gut. This way the holding paddock can be inspected for seedlings and they can be controlled early.

Control plants before flowering to minimise seed production. Monitor and control regrowth of new seedlings in treated areas.

Physical removal

By hand

Dig up small plants. Remove all the roots to avoid regrowth.

By machinery

Larger plants and infestations can be removed by machinery if this will not damage native vegetation. Remove as much of the roots as possible.

Chemical control

In dense infestations check for regrowth and follow up with further applications.

Spot spraying

Spray actively growing plants. Cover all the foliage with the herbicide mixture.

Cut stump method

Cut trunks or stems and apply herbicide to the stump within 15 seconds of cutting.

Herbicide options

See Using herbicides for more information.

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Metsulfuron-methyl 300 g/kg + Aminopyralid 375 g/kg (Various products)
Rate: 20 g per 100 L of water and a wetting agent at 100 mL/100 L.
Comments: Thoroughly spray all the foliage and stems until wet. See list on label for suitable wetting agents.
Withholding period: Pastures - Grazing for meat production or cutting for animal feed: Do not graze for 56 days after application. See label for further details
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors) + 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: High/Moderate

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Metsulfuron-methyl 600 g/kg (Various products)
Rate: 10 g per 100 L of water
Comments: Spray to thoroughly wet all foliage, but not to cause run off. Apply to actively growing plants before flowering. Add wetting agent.
Withholding period: Nil (recommended not to graze for 7 days before treatment and for 7 days after treatment to allow adequate chemical uptake in target weeds).
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors)
Resistance risk: High

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Picloram 44.7 g/L + Aminopyralid 4.47 g/L (Vigilant II ®)
Rate: Undiluted
Comments: Cut the stump then apply a 3–5 mm layer of gel for stems less than 20 mm diameter. Apply 5 mm layer on stems above 20 mm diameter.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Biosecurity duty

The content provided here is for information purposes only and is taken from the NSW Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area	Duty
All of NSW	General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.
Greater Sydney	Regional Recommended Measure * (for Regional Priority - Prevention) The plant should be eradicated from the land and the land kept free of the plant. The plant should not be bought, sold, grown, carried or released into the environment.
Hunter	Regional Recommended Measure * (for Regional Priority - Eradication) Notify local control authority if found. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant.
North Coast Exclusion (eradication) zone: Bellingen Shire LGA, Clarence Valley LGA, Lord Howe Island, Port Macquarie-Hastings LGA. Core infestation (containment) zone: Ballina Shire LGA, Byron Shire LGA, Coffs Harbour City LGA, Kempsey Shire LGA, Kyogle Shire LGA, Lismore City LGA, Nambucca Valley LGA, Richmond Valley LGA, Tweed Shire LGA.	Regional Recommended Measure * (for Regional Priority - Containment) Whole of region: Land managers should mitigate the risk of the plant being introduced to their land. A person should not buy, sell, move, carry or release the plant into the environment. Exclusion zone: Notify local control authority if found. Land managers should eradicate the plant from the land and keep the land free of the plant. Core infestation: Land managers should mitigate spread of the plant from their land. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value.
South East Containment zone: Wollongong Local Government Area. Exclusion zone: Whole of region except containment zone.	Regional Recommended Measure * (for Regional Priority - Containment) Whole of region: Land managers mitigate the risk of new weeds being introduced to their land. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Within exclusion zone: Land managers should eradicate the plant from the land and keep the land free of the plant. Notify local control authority if found. Within containment zone: Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value. Land managers should mitigate spread of the plant from their land.
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here

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Reviewed 2026